1. Field of the Invention
The present application relates generally to computer systems.
2. Description of the Background Art
Virtual machines use a single physical computing machine, with one or more physical processors, in combination with software which simulates multiple virtual machines. Each of those virtual machines has, in principle, access to all the physical resources of the underlying real computer. The assignment of resources to each virtual machine is controlled by a platform manager or virtual machine manager(VMM). A typical VMM controls the physical resources of the system and presents a virtualized hardware for each of the virtual machines (also called Guest Operating Systems or Guest OS'es) running on top of it. The VMM intercepts all hardware related instructions from the Guest OS'es and executes the appropriate instructions on the real hardware, after ensuring security and isolation/separation of the Guest OSes from each other, after verifying entitlement and availability of the hardware resource in question for the requesting Guest OS, and doing any mappings from the virtual hardware world to the real hardware as appropriate.